1. Field of the Invention
The present invention relates generally to telephone communications, and more particularly but not exclusively to methods and apparatus for protecting telephone users from caller ID spoofing.
2. Description of the Background Art
Caller ID (identification) allows a telephone user to identify a caller before answering a telephone call. A caller ID corresponds to the caller's telephone number and is displayed on the called party's telephone or caller ID apparatus. This allows the called party to make an informed decision as to whether or not to answer the call. Telephone users have relied on caller ID to screen unwanted callers, such as telemarketers, fraudsters, and the like. The advent of caller ID spoofing techniques makes caller ID unreliable. In particular, voice over Internet protocol (VOIP) has allowed “spoofing”, i.e., faking, of caller ID relatively easy. With caller ID spoofing, the displayed caller ID seen by the called party is not the real telephone number of the caller. Caller ID spoofing is dangerous because callers can abuse it to impersonate banks, friends and family, credit card companies, and other trusted callers by faking the caller ID to display the trusted caller's telephone number. Worse, there are publicly available caller ID spoofing services, such as those provided by Spoofcard, PhoneGangster, Spooftel, and Telespoof.